1. Field of Invention
The present invention relates to a noise elimination method of video signals, and more particularly to a noise elimination method of an image sequence which is integrated with 3D noise filtering during color separation by using color filter array interpolation (CFAi).
2. Related Art
Generally, noises occurring in an image include impulse noises, salt and pepper noises, and Gaussian noises, among which the Gaussian noises mostly conform to the noises generated by an image sensor. Mean filters, median filters, and Gaussian filters are common in 3D noise filters. The mean filter and the median filter are both linear filters, which mainly employ a filtering method of directly adding pixel values of adjacent images or adding the pixel values after being multiplied by a weighted value and then obtaining a mean value thereof to replace an intermediate pixel value. The Gaussian filter applies the normal distribution characteristic of Gaussian function, and selects an appropriate smoothing parameter (σ) to control the extent of eliminating the noises. In addition, methods of eliminating noises by using Fourier transform and wavelet transform are also available.
The noises randomly occur in an image sequence, existing 3D noise filtering technologies are all applied to spatial space such as full RGB or YCC color space, and most 3D filtering processes applied to video signals (or image sequences) are performed after color separation through color filter array interpolation (CFAi). However, the noises may affect results of the color separation through CFAi and the subsequent processes, and meanwhile the processing results of the above processes may also affect the correctness of motion estimation. Moreover, artifacts generated by the noises in the color separation through CFAi may also affect the correctness of motion estimation.